Sybase: fix datatype mapping; IDENTITY

[perlpunk]

Datatype mapping must also be done for identity fields
IDENTITY comes after the datatype, not before

[perlpunk]

There are two other issues:

1. DBIC deployment_statements can receive a list of statements. The sybase sqlt producer returns a single string which is then splitted by DBIC. The producer should return a list in list context. I made the same change in the postgres producer some years ago.
2. In Sybase, you can't deactivate constraint checks. So depending on the order of the CREATE statements it will fail because of missing tables for foreign keys. A solution would be to add the foreign key creation to the end of the statements.

Maybe I should do this all in one pull request?

[perlpunk]

see #67